1. Field of the Invention
The present invention relates to optical equipment, in particular a lens position-control device for controlling a lens driving device.
2. Description of the Related Art
Hitherto, various attempts for low power consumption have been developed in digital cameras. As a result of one of these attempts, there is known a structure for reducing power consumption by a step motor used in an image stabilization mechanism, as described in Japanese Unexamined Patent Publication No. 2006-158019. In this structure, after image stabilization a magnetic pole of the step motor is moved from its stopping position to a more stable position and thereafter, the supply of excitation power to the step motor is stopped. With this structure, it is possible to prevent image blurring caused by an expected movement of the magnetic pole to the stable position at the time of imaging, and it is also possible to reduce power consumption of the step motor. This structure is also applicable to an autofocus mechanism for controlling the lens position with the use of a step motor.
In the application of the above-mentioned structure for an autofocus mechanism, however, a problem arises when the magnetic pole is simply moved to a position requiring low power consumption. This is because the stopping position of the magnetic pole is associated with the stopping position of the lens. Namely, there is a possibility of image blurring after the movement of the magnetic pole despite completion of a focusing operation before the movement of the magnetic pole. This image blurring has a tendency of gradually intensifying as the light-receiving pixel pitch decreases. In recent years digital cameras have come equipped with an image pickup device whose number of pixels has been dramatically increased to provide high resolution images, and therefore, image blurring should be eliminated since the light-receiving pixel pitch of such a digital camera is small. Therefore, an object of the present invention is to provide optical equipment capable of stopping a lens, namely, a magnetic pole in a position producing no image blur and requiring low power consumption.